Notes for Chapter 5 on Tissues

Transcription

1 Notes for Chapter 5 on Tissues Four major types of tissues 1. Epithelial 2. Connective 3. Muscle 4. Nervous 1. Epithelial Tissues Epithelial tissues have different characteristics than the other 3 groups They are widespread in the body They cover, line, and have one free (apical) surface They do NOT have a blood supply They have closely packed cells with little background (matrix) They are classified by layers and shape They are attached to connective tissue via a basement membrane Classification of Epithelial by shape and layers Single layers are called simple Multi layered are called stratified A falsely stratified type is pseudostratified Cells that are flattened are squamous Cells that are cube shaped are cuboidal Cells that are rectangular are columnar Cells that change shape are transitional Simple squamous epithelium Single layer of flattened cells Large centrally located nucleus Functions are filtration and diffusion Locations include: walls of capillaries, alveoli of lungs file:///c /Documents%20and%20Settings/MHUSS/Desktop/Chapter%205%20-%20Tissues.htm (1 of 9)6/5/2006 2:17:46 AM

2 Simple cuboidal epithelium Single layer of cube shaped cells Centrally located nucleus Functions are secretion and absorption Locations include: kidney tubules and ovaries Simple columnar epithelium Cells are rectangular shaped Nucleus at bottom Functions are secretion and absorption Locations include: lining of uterus, stomach, intestine Special cells include: goblet cells (mucous) and cilia Pseudostratified columnar epithelium Cells appear striated May have cilia and goblet cells Locations include: respiratory and reproductive systems Functions: secretion, propulsion of mucus by cilia Stratified squamous epithelium Many layers of flattened cells Basement membrane obvious Cells near free surface are dead Locations include skin (keratinized tissue), mouth, throat, vagina, anal canal (nonkeratinized) Function: protection Stratified cuboidal epithelium 2-3 layers thick Rare in body Locations include: lines ducts of mammary glands, sweat glands, salivary glands, and pancreas Function is protection/secretion file:///c /Documents%20and%20Settings/MHUSS/Desktop/Chapter%205%20-%20Tissues.htm (2 of 9)6/5/2006 2:17:46 AM

3 Stratified transitional epithelium Changes in response to tension Found only in urinary bladder, ureters, and urethra Function is stretching Stratified Columnar Epithelium Rare in body 2 or 3 layers thick Found only in vas deferens and parts of pharynx Glandular epithelium A gland consists of one or more cells that make and secrete a product Exocrine gland secretes it s product through ducts Endocrine glands do not have ducts, but secrete product directly into blood stream Exocrine classification is by function and structure Structural include unicellular like a goblet cell, and multicellular Functional classification includes: Merocrine glands (secrete product by exocytosis), apocrine glands (product and a portion of cell are released), holocrine (product released inside an intact cell) 2. Connective Tissue Occur throughout the body Most abundant tissue by weight file:///c /Documents%20and%20Settings/MHUSS/Desktop/Chapter%205%20-%20Tissues.htm (3 of 9)6/5/2006 2:17:46 AM

4 Functions are: support, protection, fill spaces, store fat, produce blood cells, protect against infection, repair tissue damage, and serve as a framework Major characteristics Have a blood supply (except cartilage) Have a lot of matrix and Cells reproduce Cell types include: fibroblast (most common type), macrophages (carry on phagocytosis), mast cells (release heparin to prevent blood clotting) and histamine (that is an important chemical in inflammation and allergic reactions) Fibers include: collagenous (thick, contain collagen protein), elastic fibers (contain the protein elastin), and reticular fibers (thin collagenous fibers that are highly branched) Classification Loose connective tissue Adipose connective tissue Reticular connective tissue Dense connective (regular and irregular) Elastic connective tissue Cartilage (hyaline, elastic, and fibrocartilage) Bone file:///c /Documents%20and%20Settings/MHUSS/Desktop/Chapter%205%20-%20Tissues.htm (4 of 9)6/5/2006 2:17:46 AM

5 Blood Loose connective Also known as areolar Contains fibroblasts that secrete collagenous and elastic fibers Abundant Locations; binds skin to underlying organs, fills spaces between muscles Adipose Also known as fat Stores fat in adipocytes Found beneath skin, in spaces between muscle, behind eyeballs, around organs Reticular connective Forms the stroma (background) of many soft organs Contains reticular fibers, and collagenous fibers Locations include liver and spleen file:///c /Documents%20and%20Settings/MHUSS/Desktop/Chapter%205%20-%20Tissues.htm (5 of 9)6/5/2006 2:17:46 AM

6 Dense Connective Dense regular has collagenous fibers in bundles with fibroblasts in rows between bundles Examples are tendons (connect muscle to bone) and ligaments (connect bone to bone) Dense irregular has randomly arranged collagenous fibers and are found in joint capsules for example Elastic connective Contains yellow, elastic fibers in parallel strands or branching networks Found in attachments between vertebrae (ligamenta flava) Also found in walls of some hollow organs, heart, and larger airways Cartilage Provides support, frameworks, attachments, protection, and a template for developing bones Contains chondroblasts that secrete matrix 3 types of cartilage include: file:///c /Documents%20and%20Settings/MHUSS/Desktop/Chapter%205%20-%20Tissues.htm (6 of 9)6/5/2006 2:17:46 AM

7 a. Hyaline cartilage-found at the ends of bones, is the most common type of cartilage, and most of your bones were made from a template made of hyaline cartilage. The lacunae are scattered thorough a smooth matrix. No visible fibers. b. Elastic cartilage-this cartilage makes up the ear. It has lacunae, chondrocytes, chondroblasts, and fibers in the matrix. You may think the lacunae of this one looks like an owl face. I do.!! c. Fibrocartilage Found between vertebrae (intervertebral discs) Also found at junction between pelvic bones (symphis pubis) Strong, has many collagenous fibers so slides appear very wavy. Bone Most rigid connective tissue because it contains calcium salts Microscopically forms an osteon or haversian system Protects and supports and helps provide movement (with muscles) An osteon contains a central (haversian canal), canaliculi, lamella, lacunae, and osteocytes or osteoblasts. One other type of bone cell is called an osteoclast. This one is responsible for the breaking down of bone. file:///c /Documents%20and%20Settings/MHUSS/Desktop/Chapter%205%20-%20Tissues.htm (7 of 9)6/5/2006 2:17:46 AM

8 Blood 3 types of cells: red blood cells, white blood cells, and platelets Fluid portion is plasma Produced in hematopoietic tissue of red bone marrow 3. Muscle Tissue Contractile 3 types including skeletal, smooth, and cardiac Skeletal is voluntary and striated Cardiac is found in the heart, is involuntary, striated, and contains intercalated discs Smooth is non-striated, is involuntary, and is found in intestines, stomach, urinary bladder, uterus, and blood vessels 4. Nervous Tissue Contains specialized cells called neurons Are able to sense change in environment and send signals (nerve impulses) to and from the brain Have an axon, a cell body, and a dendrite Have neuroglia that support and bind the components of the file:///c /Documents%20and%20Settings/MHUSS/Desktop/Chapter%205%20-%20Tissues.htm (8 of 9)6/5/2006 2:17:46 AM

9 nervous system, but do not generate nerve impulses Additional materials in chapter Look for clinical applications boxes throughout chapter Go to on-line learning center for this textbook. file:///c /Documents%20and%20Settings/MHUSS/Desktop/Chapter%205%20-%20Tissues.htm (9 of 9)6/5/2006 2:17:46 AM